Trunking system of radio distribution



E. E. CLEMENT TRUNKING SYSTEM OF RADIO DISTRIBUTION'.

` Filed March 26. 1925 4' sheets-sheet 1 April 15, 1939.

y E; E. CLEMENT I TRUNKING SYSTEM QF RADIO DISTRIBUTION t.1 Sheets-Sheet 2 N QN..

- April 1 5, 1930.

E. E. CLEMENT ynuoo nLrLnLnm.

TRUNKING SYSTEM-or RADIO DISTRIBUTION Filed March 26, 1925 4 Smeets-sheet 's www# 31a/vanto:

April 15, 1930.v

E. E. CLEMENT TRUNKING SYSTEM OF RADIO DISTRIBTIQN Filed Mrch 2G, 1925' A' l .ators lamp and J'ack-switch-Stlillsi mentes Apr.- 15,193@

' Awel smit-s'wwwam@ .EDWARD nomm, .or WASHINGTON, i; Drsmnxc'r or contratan;v AssIeNon, 'row Enwnnp r. conLADaz, or wasnmo'rom DISTRICT or conmu- TBUKKINQ B YSTEIM'. OE RADIO DISTRIBUTION 'Ap'pne'uoi med maren 26, 1921's. "serial mi 18,529.-A

' The 'present invention relates-to systems of radio broadcast distribution and .has for-its object thre organization -of such a system -so thata program. maybe originated,'relayed and distributed :over a large area, uniformly and in a systematic and .orderly `manner to authorized users or subscriberswho will get the full, benetit'of the use of vacuum tubes .in receiving andamplifying'without the ne '1a cessity of maintaining'tubes at vtheir stations;

the tubes used by the -subscribers in receiving being located at central points, where supervision, maintenance powersupply and control may be centralized and put under .the 1a control of e ert operators'.

vr*The invention is'a'p'plicable'to manuahaui tomatic or 4s emia'utomatic 'telephone systems;l the principles involved not being changed by I different methods of eiecting or con-trolling 'the -necessary electrical .Tswltching connecff jtions.-`

. My invention1 is illustratedin .the accom-- panyingdrawings, in which l Figs. 1- and 2 indicate diagrammatically, 'the telephone 'exchange lportion and the x broadcast distributing portion, respectlvely,

of a subscribers central station forming part lof a systemembodyingmy invent1on.

' 3 is a modification of the broadcast,

f Fi 4 is .a further .modica-tionfdf the broa cast,A distribution, switching systein.

Figs. 5 and 6 are detail views of .the 'oper-j :Referring'to the drawin s in detail and first to`Fig. 1, this shows t e' essential circuits of an ordinary telephonejexchange sys- I. tem in which ,lf-J areline terminal .jacks formingthe terminals of telephone lines lead 40 mon battery cord circuit shown. The cen- Where service -individually associated with the line. Thus,I

ing to stations/ to beinterco'nnected su'chas-f j the subscribers station A.l These jacks are A arranged-to be interconnected through thev .11sual' answering andfcalling plugs P-P forming the terminals of the usual com- 45 Qtral oilic'e' terminals, of each. 'line are provide 1 with the usual line relay L., line lamp' L2 'and cut-off relay La; 'isftobe metered a recording meterMis also the circuit arrangement here shown is that .of the standard multiple switchboard, comf,

'mon battery,l telephone exchan e system, and n as such is well understood in t e art further. detailed description thereof will be here de- .ferred and brought out later in the descriptionof o eration. In-addition to the usual l line terminal, multiples 1, 2 and V3, representing multiples of the tip, sleeve and test i or c ut-oif circuits, respectively, I provide a -fourthconductor 4 leading-ironia ,contacton the line relay along with themultiple conductors 1,-2 and 3 to. the broadcast distributingsystem diagrammed in Fig. 2. .Fig. 3 'shows thelb'roadcast distributing .66' system of which the portion to the left of the dotted line is situated-at 'the centralfoice' and connected with the subscribersltf'elephono line terminal apparatus ofthe 'telephonecelr tralC (Fi-g. 1') through 'conductors 1 2, 3 7o .and 4,while the portion tothe right -offthe' .1 5 4, dotted line in Fig; 2 is situated at the-Subscribers substation and. connected withthe subscribers telephone-substation apparatus' .AC-(Fig. lI-)'t'hroughthe multi le conductorsj- 755 and 6,* tiples 1 2 terminate in the spring contacts 7 8 of`a jack 9 which contacts are arranged upon the insertion of the dummy pl '.10 to be spread apart to engage with the stationary 80 -contacts .11 -12 toextend the connection 'of through the winding'lof a repeatin coil Se 19 'whilefthe conductor-.14 'connects wit the" i 'negative terminal of the. battery'B? through .a sleeve or supervisory relay 42 and the wind-A ing 16 of a repeating coil'20. .1

AA radioreceiving set, individualtothe line, is. arranged 'with its! output circuit 2142. connecte-d in segieswith the windings 17.-18 of the .repeating coils 19and 20; and .5. the plate battery 13. v This receiving set comprises in general, a detector tube 23 and am# 954 plifyin'g tubes '37 arranged'with suitable cirf cuit connections *and other .apparatus to form a simple regenerative receiver withl one stage of .audio-frequency amplification as shown. The detector tube has its .tuned input circuit cuit 26 coupled to the input terminalsof the amplifier tube 37 through an audio-transformer 27, the plate circuit 'of the tube 23 being also coupled to input circuit 24 through a suitable feed-back coil 28. A lament hat .tery 29 supplies the filament ot both tubes through a suitable switch 30 and a plate cire cuit battery 41 is includedin Vthe plate circuit 26 of the detector tube. It is to beunderstood that' this receivin set is typical only and m'aybe substituted by any known or other suitable set Vca able of receivin radio signals and putting t e same on the su scribers line extensions 13-14 through the repeating coils 19-7-20.4 Other antennas such as 43 and .44 are provided for other sub-' scribers receiving sets, the same as that shown. A normally closed' contact 31' on the 2o relay 42 connects the-common batteryB to the conductor 32 which terminates in a norv mallyop'en contact 33 in the jack 9 operable to 'extend the connection of conductor 32 to potential thereto. This .signal conductor is arranged to be connected with battery upon A* energization of the subscribersline relay fthrough lthe line relay contact 52, Fig. 1.

The relay 42, 2 also controls the connection ,of the m tiple test circuit conductor 3 to the common battery B through a normal- -ly open contact 34"which connection'includes a special tone test device of any known `or othersuitable form, indicated diagrammatically at 35, operable to suplerpose. acharacteristic signal current on t e .test conductol` 3. Connected between the signal conductor 4 and ground is a signal 'lamp 36 mounted near the jack 9 in the mann r of the usual .telephone line or call' lamp. he subscriber at substation A 'is provided with a radio broadcast receivingset A, multipled onto the line 69-70 through multiple conductors 5-6 and comprising an arrangement of ap.- paratus elements and .circuit connections similar to those of the regular common bat- 4- tery telephone set A. except that the usgal switchhook is'replaced bya jack J arranged to cooperate with the plugl?" of aloud speak- 59 er receiver 64 which takesthe place of the usual receiver. Thus the jack J is so 'ar- I ranged that when engaged by the lylg the primary coil 60 of the booster co transmitter 62 and key 63 will be connected` in series across the lme throu h multiples 5.-'-6,Yand the receiver 64 will e in a local series circuit including 'ary winding 65 Vand condenser266. 'radio broadcasting station generally by the dotted line enclosure 45,'is amPPe@ vices as indicated at 46 and 49 which may be of any known or other suitable type, prefsmd- 55 apparatus as symbolize by the au `the' signaling conductor 4 to supply battery connected indicated with one or more transmitting de erably a combined rela 'g and .originatingv transmitting antennas 47-48 andthe input microphone M. The radio broadcasting station 45 is also equipped with a subscribers 'telephone substation apparatus A2 and broadcast receiving set A2 like the apparatus Af and A1 and connected with the central station C`by line wires lOl-102, where they. terminate "in, vline terminal .apparatus sznllar to that ofthe line 69--70. This terminal apparatus, like that of the substation A and .line 69-70, is provided with multiple conductors 221-222-'223 and a signaling conductor 224 corresponding in' function to con- 1ductors 1, 2, 3 and'4 respectively,'of the terminal a paratus of substation A The roadcasting station 45 -is also connected with other telephone .central -exchanges, furnishing radio broadcast service to'its subscribers, through subscribers substation equipments such `as that indicated at :v2-w1". Inplace of this one line 101e-102' maybe used in connection with trunk lines not shown for connection with such other exchanges through exchange C. (Fig. 1).

In operation, assuming one or more ofv the.

broadcasting transmittersat the station 45 to be` transmitting, the subscriber at substation A desiring broadcast service, now connects his broadcast receiving-or extension set A10 to the line by inserting the receiver .plug P2 in the jack Jn which connects his receiver 64 across the line multiples 5 and 6 through the 'booster coil .windings 60-63 and condenser ,266 in series, and closes a ath, for direct current between' the multip es 5 and 6 10o through coil 60, lower spring of jack J, transmitter 62 and signaling key 63. v

. .This energizesthe subscribers line relay "lat the centraloice in the usual mannerby back to battery B. Actuationof the line'rel lay energizes the line lamp. Lz by closure of a local circuit which me be'traced from common battery B throug circuit elements. L2, 71, 68, and back to batteryB. This causes the line lamp L? at the'tele hone operators switchboard to glow, but on y for a moment, -as they subscriber :wantingl broadcast service' tfwilljmmediatelyo erate rapidly open and c oseyhis line circuit which -causes hisline'to flicker insteadl of glowing steadily an so'in'dcate to the telephone operator (Fig. 1) that the subscriber 41s not calling for.- a telephone connection.l 125 This intermittent yactuation of the sub-4 scribers telephone line relay L" also causes a flickering oftheflamp 36 (Fig. 2.)4 asso-v ciated with-his broadcast service,`multi le' ja c k 9 situated before the broadcast service 130 is signal key 63 to 120 l 1p may be traced from .battery B `through circuit elements, 15, 1.3, 11, 7, 1, into Fig. 1), 69, 5, (into Fig. 2), 60, 62, 6,

' operator. This operator'perceiving the flickv ering of the lamp interprets the signal as a call for broadcast 4service -and in answer thereto inserts the actuating plug in the -jack 9. This effects the closureof contacts 7-11, 8--12, and 33. Closure of the contacts 7.-'11, 8-12, connects the battery B (Fig. 2) across the subscribers line through the repeating coil windings 1'5-16 and the sleeve supervisory relay/12 which connection (Fig. 2)

into

L Figv 1) 70, 2, (into-Fig. 2)- fs-.12, 14,' 42, 16,

" fsignal lamps is held energized over the test conductor 3 by battery su plied theretothrough the special 'tone test evice 35, a 'telephone operator in l testing the line will receive this characteristic -tone test instead ofthe usual click in the ear indicating that the subscribers ,line is busy Vback to battery B.' As thiscompletes the circuit including the battery B and the relay 42 this relay is energizedand closes the circu1t of thecut-oif relay Ls (Fig. 1) over a athwhich may be traced from the common attery--B (Fig. 2) through the circuit elements 35,' 34, 3, (into Fig. 1), cut-0E relay L, 68, and through'ground back to common battery Energiz'ation. of the cut-off relay disconnects the subscribers line from the te] ephone line-signal apparatus in the usual manner, thus causing the line lamp'L to become deener ized and extinguishing both i and 36. As thecut-o relay with -the special or broadcast service which may' or may)7 not be interrupted for telephone servicey according to thewishs of the subscriber. Assuming the inputcircuit24 (Fig: 2) vof the subscribers central otlice receiving set to be tuned to the'frequency of the waves 'transmitted bythe antenna 48, these waves will be received and detected by the detector tube 23, and the audio signals transferred through thel intertube audlotransformer 27 to the amplifier tube 37, from whence they will pass, amplified through the repeating coils 19-'20 onto the subscribers line multi- .ples 13-14 and consequently out over the subscribers line tothe substation -radio receiver A19. The' circuit of' the audio si nal l currents from the secondary winding o the repeating coils 19-20. to the. subscribers substation receiving set A10 may be traced from i common battery-B (IFig. 2)v through circuit s elements 15., 13, 11, 1' (into Fig. 1), 69, 5 (into Fig. 2), 60,. 89, '62, 63, 6 (into Fig.'1),

multiple resistance, 16 and back to battery B.

.The broadcast signal currents passing in circuit with the subscribers broadcast tell ephone receiver 64`which may be traced from .fthe coil 65 throughci'rcuit elements J 2, P2., 65

64,. P=, J1, 89, 62,163,266, back to @on 65.

common battery B. This causes the lamp 36 to glow steadily indicating to the'broadcast service operatorfthat a disconnection is de-- sired whereupon the operator pulls the plug 10 which opens all the contacts vof jack 9 and restores the circuits to normal. While, for the sake of simplicity, a manual switch 30 is shown for use in controlling the energi'zatlon of the tubes 23'and 37 which switch may be closed and 'opened by the radio operator in .connecting and disconnecting the subscribers line for radio service, vit 'is' to be n understood that the switch 30 may be replaced by a pair of normally open contacts on .the relay 42 .for automatically performing this lfunction.

. In practice, instead ofI maintaining the sub-' y scribers central office receiving set always tuned to al given wave length, the set may be provided with means controlled by the radio operator for varyingits tuning to=permit the l subscribed to receive any one of a plurality of programs. In this'case the subscriber desiring a change ofprogram would signal the radio operator by flashing the lamp 36 wher'eupon the operator perceiving the signal and v noting the plug 10 to be already in the jack;-. would connect her 'listening set with the line by engaging the plug' extension terminals 51-.52 with the clip contacts 53-54 and, a

certainingthe program wanted,- would tune the subscribers receiver to -the desired program. Where a group of programs with a vseparate announcer program is used, as disclosed in my copendmg application, Serial No. 10,916, filed February 21. 1925, the subscriberscentral office receiving set would preferably be normally ,tuned to the announcer program.A Iii-'Fig 3 is shown a modified arrangement of central o'ice broadcast distributing apparatus which may be substituted for that of Fig. 2, where it is desired. to make the central oflice receivingv sets interchangeable with different lines to permit the use ofa number of -sets less than the number of lines. to pr nit 70,2 (into Flg. 2), 8, 12, '14, relay 42 and its a quick interchange of sets should one get out of order, to permit program selection by selection of different sets permanently tuned.

or to give the subscriber choice of different kinds of sets. Broadly, this arrangement the same as that of Fig. 2 except that the snbscribers multiple conductors 1, 2 and 4 are arranged to be connected withA any one of a number of receiving sets, such as that com- CROSS REFERENCE prising the tubes 23 and 37, through a selector switch 55, while the busy'test multiple '3 is arranged to be connected with the battery andv tone test device 35 through'an off-normal contat.`59 of the switch 55. The switch 55 is individual to the subscribers line having its Wipers 56, 57 and l58 connected to the multiples 1, 2 and 4 respectively, and 'each ar ranged to cooperate `with a bank of contacts for connection with any one of a number ofl receiving sets, the set here shownl being connected with the irst contact in each banli.

through-conductors 13, 14 and 32 corresponding to those similarly numbered in Fig. 2;

The operators telephone-set 50 is the same as that of Fig.` 2 exce t that it terminates in an ordinary two -con uctor plug P adapted 'to engage the jacks' 9 to connectthe set across the line multiples 1-2.

In the operation of the system, using the arrangement of Fig.'3 in place of that of F\ig.- 2 the subscriber at station A19 during broadcast service, signals the radio-operator by 59 which connects the battery 'B and .tone test device to the test conductor 3 to energize the subscribers cut-oil relay and apply the characteristic radio, busy-tone test to the test wire 3, while engagement of the switch arms 56 and 57' with the contacts forming the ter minals of the set selected, completes the connection of the secondary winding of the re-` peating coil of that set to the line multiples which connection may be traced from com` monbattery B (Fig. 3) through circuit elements 15, 13', 56, to line multiple 1, and from multiple 2 through 57, 14, 42 and 16 back to battery B. Should the subscriber desire his set to be tuned to a special program he may signal the radio operator by again flashing the lamp' 36, who can ascertain his wants through the use of her telephone set and tune the radio receiving set as required.

When the subscriber desires to discontinue th'e radio service he withdraws the plug of his radio receiver, which opens his line circuit as before described in connection with Fig. 2, and as the relay, 42 (Fig. 3) is included in the line circuit it now becomes deenergized permitting the contact 31 to close and energize the lamp 36 in a circuit which may be traced from battery B lthrough circuit-elements 31, 32', 58, 4, 36 to ground and back tol battery B. The operator observing the continuous glowing-of the lamp will now return'the switch 55 to the normal position shown which will disconnect the line and open the` normally open contact 59 deenergizing'the subscribers cut-ofi relay and removing the busy test.

In the use 'of either the arrangements of Fig. 2 or Fig. 3, the radio operator may test thel qualityof reception furnished by thereceiving set connected tothe subscribers line by use of her listening set 50 Also, as the broadcast station45 is provided with a subscribers broadcast receiving set 4A2" connectstation 45 may test the quality of reception EXAEWNE? of the matter beingbroadcasted from that station simply by lca ng for service from the telephone central station, and getting connection for the program to be tested in the same manner as that of any subscriber, for

example like that set out in the foregoing description of operation.

In Fig. 4 is shown a modified arrangement for switching the. subscribers line into andout of operative connection' with 'a 4central ollice receiving set, which is like that of Fig.

2, except that the jack and repeat plug ar-A rangement 9 and 10. is replaced by a )ack switch and push-pull button 100, andthe connection of .the busy test device ,35. with the test wire 3 is controlled through a contact on the jack-'switch 90 instead o a contact on the supervisory rela 42. In practice a numbf-r of the jack switches together with theirl corresponding line lamps 36 are mounted on a common strip 300, as shown in detail in Figs.

5 and 6. The'mounting strip 300 comprises an upper section 301 and a lower section 302 of insulating material in which are embedded the vlamp jack vsprings; .304-305 'andy jack;

switch springs 80-f120, etc. Infront of the spring mounting strip 300 is, mounted a` A:tace strip or plate 306 provided along its upper portion with apertures 307 through,

which the lamp 36 may be'inserted between the-lamp, jack-springs 304-305, and in which is mounted the usual telephone lamp ewels 308. A guide rod`309, which has bearing in both the front plate 306 and the back munting strip 300, carries a wedge bar 310 and an actuatin push-'pull button 100,.;the wedge bar 310 mg arranged, u on inward moveinent, to pass between the ner pair-.of each of the sets of jack-switch springs, spreading the inner 'springs into contact wlth their complementari-opposed springs as will be clear from the diagram of Fig. 4. To enable the operator toconnect hen listening set, like that shown e650 in Fig. 2, with the line, line extension lugs 315 (Figs. 4 and 6) are provided nea-r each button 100, the lugs bein mounted in tlie': face late 306 and connecte by wires 316 withyt e line contact springs In the operation ofthe system using the switching circuits and apparatus of Figs. 4

to 6, the subscriber callsthe broadcast opera- 70 ed with t-he'central stat1on, an operator at the I .the back Contact l31 ofthe rel may bef traced* from battery (Fig. v"4)- through circuit elements' 15, 13,110, 70, to line multiples l'and' from line multiple 2 contacts 330 connects the signal wire 4 with a forthe same purpose as that oi, the similar connection in Fig-2.' The'closure of contacts '10 340 completes aconnection' from the test or Y 'cuto'f wire 3 through wire 341 and special tonetest device 35 to the ungrounded side of 'battery B, -thus observing thesame function as that of the relay contacts 34 ofFig.- 15.2.' When the subscriberde'siresto discon-v tinue the broadcast service,` he disconnects his broadcast receiving apparatus (Fig. 2)' thus 'causing the broadcast service-line-lamp 36 to glow -steadily allin the 'same 'manner 'as bei Qq fore described in connection with Fig. 2,

` whereupon the' operator will ull the button 100.1'estoring the circuitstot e normalcondition'shown. 4 It is to 4be noted the' subscribers radio receiving apparatus i .-(here shownfragmentarily for 'the sakeof:

plea'rness') is controlled through a'normally pen contact350 on the supervisory relay 42,

which contact, willbe' clearly understood',

the filament circuit .switch l radio busy test circuit for the-line a radio' takes the place. of 30 of Figs. 2 and 3.

AA. further modifcation of the invention which I propose to'make use. of is to omit the supervisory signal contact 31 vfrom the as supervisory lamps, inasmuch as they glow only during use ot the 'receiving set, the opproperly shielded to prevent inductive orl capacity coupling between the same. In the use-of the switching arrangement of Fig. 3,

-50 this system will aord a simple and' direct means for determining what sets are busy,A

thus avoiding the.necessit for extra busy test circuits andsignals or the broadcast service operator.

It is also to be'understood that in all or in certain ones of the radio receiving sets the two audion tubes maybe connected as a detector and heterodyne oscillator to form a heterodyne receiver arranged to transmit the resulting beat wave out over the subscribers line to be detected at the'subscribes'sub- 'station by suitable apparatus such as a crystal detector.

-What I claim is: 65 1. In a system of radio broadcast'distr'ibu- 42 as, and

niet in this letter einen -25 .arrangement Fig'. 4), the filament circuit ofrelay 42 and usetheaudion tubes such as 37 'erator being rovided with a suitable reflecting system a o rding observation of the tubes tion, a telephone central station with 'subscribers substations and wire lines interconnectin'g them, a telephone switchboard and a radio switchboard at said central station, radio 'receiving means'at the central s tation '7o adapted to be connected to an individual subscribers line and operable to receive and r e -lay,ra dio' matter over the line to the substa' tion at a' frequency suitable for line transmission, each line connectin means forming afunit in the radio switch oard and com' Aprising the following elements: a line switch, actuating,means'therefor, a line extension circuit leading therefrom to said radio .receiv- Y ing me'ans,' a radio busy test circuit for theline, a radio-clearing out signal circuit for the line, and terminal means connectedwith the line for' supervisor purposes..

2. In a system of ra `o -broadcast distribu- "tion, acentral station with subscribers sub- 3 5 stationsand wire lines interconnecting them, A'a telephone-switchboard'and .'a radio switch' `board at said central station, and a radio receiving set'at thecentral station having its output circuit adaptedto be individual subscribers line, each-'line -connecting meansiformin'g'a unit inthe radio switchboard and comprisingthe following.. elements; a line switch, actuating means therefor, a line extension circuit leading 94'sV therefrom to said radioreceiving means, aL

clearing out signal circuit for the line, and IV supervisory pur v 100 3. Inasystem of radiobroadcast distribu'- tion, a central office 'withsubscribers substations and wire lines interconnecting thel'n', a telephone switchboard 'anda radio switch ing set at'the central .station'and means-fon connecting' the lines 'of vsaid subscribersiindiv: x vidually. to the output circuit .of said set, each.- Aline connecting means formin a unit in the radio switchboard and com rismgthe follow- 11o ing elementsz' aline switc ,actuatin n ians l. f

therefor, a' line extension 'circuit eading therefrom to saidfradio receiving lneans,'a` radio busy test circuit for the line, a radio clearing out signal circuit 'for ,the line,l and 115 terminal means connect supervisory purposes. 1

4. In a systemo-radio broadcast distribution, a district broadcast .service station, a.' telephone central station with subscribers 12o substations and wire vlilies interconnecting said subscribers and the telephone central station, radio receiving sets at the telephone central station, a telephone switchboard and a radio switchboard at said central station, ar- 125' ranged to receive matter broadcasted from said servicestation, and means'at the telephone central station for operatively connect- -111g' one of said receiving sets with the wire l 'line of one of said sbstations independently 130 connected to'an. no

terminal 'means-connected' with the Vlille vfor board at said central station, a radio receiv- `-1045 Q ed the-line for.

'foo

- telephone central'station with subscribers of the other lines', each line connecting means forming a unit in the radio switchboard and comprising the. following elements: a .line switch, actuating means therefor, Aa line extension circuit leading therefrom to said radio receiving means, a radio busy test circuit for, theline, a radio clearing out signal circuit for the line, and terminal means connected with the line for su ervisory purposes.'

i' 5. In a system o radio broadcast distribution, adistrict broadcast service station, a

substations and wire linesconnecting the subacribers stations with'the centralstatiom'one station line with one of said sets, and means at 4 mignal means connected with the line for of said substations bein .located at-the district service station, a te ephone switchboard and a radio switch board at said central station, radio receiving sets at the central sta' tion arranged to receive matter broadcasted from said servicev station, and switching means arranged -to connect .said substations over their respective wire lines each with one of saidvreceiving sets, each linev connecting means forming a unit in the radio switchboard and comprisingthe following ele-- n ments: a line switch, actuating means there-` for, a line extension circuit leading @there-v from to said radio receiving means, ai radio busy test circuit for the line, a'radioyclearout signal` circuit foi-the line, and tersuperyisory purposes. A

6. In a system of radio broadcast distribution, a tele hone centralstation with subscribers su stations and wire lines 'connecting the substations with the central station, a telephone switchboard and a radio switch board at said central station, radio rece'iving sets at the central station, means at th central station for connectin an individua subthe central oice for selectivelyvtuning said 'sets for reccption at different carrierI wave frequencies independently of each oth 'r,-each line connecting means forming a unit inthe radio switchboard and comprising the following elements: aline switch, actuating means therefor, a line extension circuit ,/leading therefrom to said radio receiving means a radio blisy test circuit for the line', a ra io clearing out signal circuit for the/ line, and terminal means connected with the line for supervisory purposes. y

. In a'system of radio broadcast, distribution, a telephonecentral station with sub-4 scribers substatins and wire lines connect ing the substations. with the 'central station,`

a telephoneV switchboard anda radio switchboard at said central station,radio receiving vsets at the central station, means at .the central station for connecting an individual substation line with one of said sets, operators tuning means at the central station for tuning thesets to diierent frequencies and means i at thecentral station for determningwhen a v V1,754,379 V 8-. `In a system of radio broadcast distribu tion, a tele hone central station with subscribers su stations and wire lines connecting the substations with the central station,

,a telephone switchboard and a radio switchboard 'at said central station, radio receivin sets vat the telephone central station, an means at the central station for connectin the 4wire line of one 'f said substations wit any one of said receiving sets selectively, each line connecting means forming a unit inthe radio y, switchboard and comprising the fol- -lowing elements: a line switch, actuatin means therefor, a line extension circuit lea ing therefrom to said radio receiving means, a radio busy test circuit .for the line, a radio 'clearing out signal vcircuit for the hne, and

with theline for terminal means connected v supervisory purposes.

9. In a system of radio broadcast distribu-l tion, a telephone central station with subscribers substations and wire linesconnecting the substatins with the central station, a telephone switchboard and a radio switchboard at said central station, radio receiving sets at the telephone central station, means for "interchangeably connecting said wire lines and-said receiving sets and means at the central station for tuning said receiving sets, each line connecting means forming a unit in the radio switchboard and comprising the following` elements: a line switch, actuating means therefor, a line extension circuit leading therefrom to said radio receiving `,means`, a radio busy test circuit for the line, a

radio clearing out signal circuit for the line, and terminal means connected with the line for supervisory purposes. i

10. In a system of radio broadcast distribution, atelephone central station with subscribers"substations and, wire lines connecting the substations with the central station. a telephoneswitchboard and a radio switchboard at said central station, radio receiving sets at the central station, ,a telephone operators line signal and a radio operators line signal for each line at the central ofiice, dif- 'ferent means at each substation for different- 1y actuating its telephone line signal and radio line signal respectively, means at the c entra-l station for connecting a line with one of said receiving sets independently'of said other lines and an operator s listening set arranged to be connected to the connected line at the radio switchboard and operablelto; re-

megeve produce the received .through said connected radio receiving set.

` v11. 4In a system of radio broadcast-di'stribu-'- tionj, a telephone centralstationfuitli subi scribers* Asubstatoiis and wire lines connecting the substations with thecentral station,

`'a-telephone switchboard and a radio switchboard at said central station, radio receiving sets at the central station, each including detector'aiid amplifying means, for receiving' modulated radio wavesand. delivering4 the' audiov frequency modulations thereon duly amplified, the output circuits of said sets beingI individually associated with subscribers I 'lines, and line terminal apparatus on the i'adiowire switchboard for each of said substation lines at' the centra-l station comprising a-telephoiie switchboard and a radio switch- ,board at'said' central station, radio receivingr I sets at the central station each incluiLng 'demodulated radio waves and delivering.the.

audio -frequency modulations thereon duly' tector and amplifying means,ffor receiving amplified, the output circuits of said sets being` individually associated with subscribers lines, and line terminal-apparatus. on the radiowir'e switchboard at the central stat'ion for each of said substation lines' consistingxot a unitary assemblage comprising a iline sig- ,l nal, a switch and a pair of linetesting terminals, sad'testing terminals being perinal 4 nently connected with the line and said switch being arranged upon-actuation to connect thc line through its corresponding output circuit v:with a'receiving set, together with an 'oper- I with any pair of said testing'terrninals indeators test circuit arranged to be connected i ".pendently'of the switch.' Y

13. Inasys't'emof radiobroadcast distribution,ja telephone-central' station with subing the substations witl the 4central station,'

scribers substations vand wire lines connecta telephone switchboard and a' radio switchboard at saidcentralstation, line switches in said-telephone switchboard for interconnecting the lines-in pairs for conversation, radio .receivingsets at the central station, each inl receiving modulatedradio waves ail'tl deliver- 'ing the audio frequency modulations thereon duly amplified, the output circuits of said sets -cluding detector and amplifying means. 'for being individually associated with subscribers lines, and a line switch 'in the 'radiov switchboard for-each line arranged to connect its line through its correspondingoutput circuit with a receiving set..

radiobroadcast distribu- I' tion t connect and disconnect said audio rei I ceiving apparatus to and'from the line, and

'14. In a system of radio broadcast distribution, a telephone cent-ral station with subscriberssubstations and wire lines connecting the substations withthe central station, radio receiving sets at the central station and Iineterminal apparatus at the central station-for each 'of said substation lines consisting of a unitary assemblage comprising aline v signal, a switch and a pair of-.line testing terminals, said testing terminals being permanently connected with the linie |and said .fswitch being arranged upon actuation to connect the line with a receivingr set, together` with an operators test circuitarranged to be )connected with any pair of said testing terminals, together with means for indicating to an operator the use or non-useof said sets. 15. Line terminal switching `and signaling apparatus comprising a plurality of units mounted on a common mounting strip` each unit comprising a line signal, a line switch,

a push-pull actuating'butt'on operable'tocon nect and disconnect the line, circuit to4 and, from an extension circuit, to'connect'and dis,-

connect a busy test circuit for the line. and

to connect and disconnect a clearingr out c'ir- 'cuit for the line'signal, respectively, and av pair of Aexposed line test terminals situated one on either side of the pusli pull button and permanently connected onel witheach line conductor.

:16; In a system' of radio broadcast distribution, a central distributing station. a pluralit fof subscribers" stations connected therewit --by wire lines, service terminals for said linesv at the central stationand means to effect connection with thelines throughsaid terminals,

an audio frequency receiving instrument at` asubscribers station, *av radio frequency receiving instrument comprising a detector tube j and amplifying means' atthe central distrib-- uting station, means lconnecting the output fof said radio receiving set directly and i'n- 'dividually to the subscribers line without going through said service terminals', with means at the subscribers station to connect and disconnect said audio'receiving apparatus to Aand from the line.

17. `In a system of radiobroadeast distribution, a. central distributing station, a plurality 'of subscribers stations connected therewith by wirelines, service terminals for said lines at the central stati'nand-means to efi fect connection with the'lines through sa-idterminals, an audio frequency receiving instrument at a subscribers station, a radio frequency receiving instrument comprising a detector tube and amplifying means at theA central distributing station, means connect- 'ving the-"outputof'said radio receiving set 1 directly), and individually to the subscribers line. without going through said service ter- -minals, with means atthe subscribers sta- H "im matter in the same manner and under the 8 muisarmv other-meansactuated in the operation of said connecting `means adapted to close and open the line respectively.

18. The radio broadcast distributing systemdescribed in claim 16, in which Vthe cen tral station radio receiving instrument is 1n- 4 dividual to and permanently associated with' 'the line circuit `from the central station to the subscribers station.

19. The radio broadcast distributing sysi tem described in claim 16, with the added element of a broadcasting station equipped with a wired line circuit extending to t distributing station, and a radio receiving set similar to the subscribers sets thereto connected, whereby the broadcasting station may receive and listen to its own broadcast same' conditions as the subscribers.

20. The radio broadcast distributing system described in claim 16, in which a plurality of subscribersstations are equipped as stated, each station having a wire circuit extending t thecentral station, with a pluraiity of individuallradio receiving sets at said central station connected to said wire circuits, and means whereby an operator at the central distributing station may listen in' and supe ,vise the transmission over each sub'- e central' 

